Disposable immersion thermocouples are known for measuring the temperature of a molten metal bath. Such structure involves a thermocouple body which is attached to the immersion end of a lance. The lance includes a coupling member for coupling contacts on the thermocouple body to circuitry associated with a recording instrument. The thermocouple hot junction is disposed within a U-shaped shield supported by the thermocouple body.
Thermocouple bodies are generally a cylindrical base made from an insulating material such as ceramic, refractory, sand, plastic, etc. The body usually terminates at the end remote from the thermocouple in a plastic coupling member supporting a pair of bare contacts.
Use of refractory materials for the thermocouple body is expensive. Fully automatic equipment has not heretofore been developed for making and assembling a thermocouple subassembly for insertion in one end of the lance since a number of operations have to be performed by hand. Ceramics and sand when used as the thermocouple body are fragile and tend to break during assembly or during shipment if they are dropped. Thermocouple bodies made from ceramic, refractory or sand require the application of heat to cure the same.
The present invention solves the problem of how to make a thermocouple body which eliminates the use of refractory and plastic materials while at the same time is made from an insulating material which will withstand immersion temperatures in a bath of molten metal for a sufficient period of time to enable a temperature reading to be obtained.